Recently, a new field of "combinatorial chemistry" has emerged which produces a "chemical library" having large numbers of members belonging to it. The library may contain peptides, or small molecular weight compounds. Expanding the positions and number of building blocks used in these libraries rapidly increases the number of possible members. As these members will be screened for various activities the deciphering or determination of the particular molecule of interest becomes a necessity. One therefore needs an efficient method to decipher the contents of the resulting library.
Many methods have been reported in the literature by which individual members of combinatorial libraries may be encoded by "tagging molecules" (hereinafter "tags"). Thus, a single molecular structure synthesized on a resin bead, for instance, is uniquely defined by a series of other, readily detectable, molecules, also bound to a resin. Individual beads are treated to release their library member, often by a process which does not displace the tag, and following identification of this compound as an "active" in a biological screen, the tags are released and analyzed to deduce the identity of the "hit". To allow for maximum diversity in a library it is critical that the chemistry used to introduce the tags is tolerated by a wide range of functionality. Thereby, introduction of the tagging molecule does not lead to undesired elaboration of the library structure, or alternatively, place limits upon the chemistry used to construct the library. Similarly, if the tag is removed prior to the library member, that conditions for removal of the tag does not destroy or react in some manner with the designed molecule.
There remains a need for the development of a molecular tag that is easy to use, readily available for detection by known means, that is stable to all the reaction conditions required to build the library, and is stable to all the conditions necessary to cleave the individual components of the library. The present invention provides for such an encoding process.